The problem is that you cannot "print preview" a report if the target printer has dropped off the network. Print Preview requires the ability to see a printer so that its print characteristics can be determined. This is because Print Preview renders the page according to the resolution and other properties set for the printer. Just as the graphic presentation of an Access form looks different depending on screen resolution settings, so it can look different based on print resolution settings.
As a test, the next time this happens, IMMEDIATELY open your Windows Start >> Settings >> Devices and check the status of your printer.
Also, remember it is possible to have associated a specific printer to a report where that printer differs from your current default printer.
One last question: Did this problem first show up on a Wednesday? (No, not kidding.) Microsoft tends to push system and driver patches every other Tuesday night, so if you caught a driver patch, something might have gotten wonky.